list view problem

Hello ranchers,
I have a layout with 2 editboxes,a button and a listview. The user fills in some data to the editboxes, and presses the button. I call a .NET webservice that returns data , in json format. I want to fill the listview with the data from the web service. I created a custom adapter and a listitem layout but i get the data but they dont display on the screen. any ideas why??